Personally, I wouldnt trust anyone BUT microsoft to update my computer as they know which files my computer requires. I have already chosen NOT to install the WGA notification stuff (Yes, it is possible), and the updates keep coming as they should.
HFNetChk pro is a utility I might consider being that it utilizes the hfnetchk program (Microsoft's OWN tool used in its MBSA) to scan for needed patches. I have yet to verify the method that the other site uses, since it's not stated on their site.